An accelerated spectral approach for predicting the vibroacoustic behavior of a stiffened pipe filled with a heavy fluid

International audienceThis paper proposes a numerical model to predict the dynamic behavior of fluid-loaded cylindrical shell coupled to two rings. The model resolution is based on the circumferential admittance approach (CAA) and a spectral decomposition of the vibratory and pressure fields. For this study, we consider four degrees of freedom in the coupling between the shell and the stiffeners. Furthermore, as we work at a low frequency range, that introduces a significant coupling between the axial/rotational waves and the flexural waves of the stiffened-shell, which contributes consequentially in the dynamic response of the coupled system. The main problem of this coupling is that the calculation of the admittances associated with the radial and the angular rotation leads to convergence issues. Therefore, to tackle this matter, an accelerated approach is proposed. The originality of the approach lies in the use of an intermediate reference calculation at a particular frequency (called reference frequency) in the high wavenumbers domain. The present approach has been proven good results in terms of accuracy and calculation cost